1. Field of the Invention
The invention relates to a tint detection circuit. Such a circuit is used in a television camera, for example for adjusting skin contours in a different way than for other tints. It is also possible to control other aspects with a (skin) tint detection signal obtained, such as RGB-YUV matrixing, color saturation, etc. The invention also relates to a camera provided with a tint detection circuit. Yet another aspect of the invention relates to a method of automatically selecting a desired tint in a video signal.
2. Description of the Related Art
A separate flesh tone contour control is described in U.S. Pat. No. 4,506,293. The contour signal of the camera is modulated with a keying signal from a skin tone detector. The circuit described in U.S. Pat. No. 4,506,293 starts from a fixed vector in the R-Y, B-Y diagram, viz. the I axis. Other cameras (Ikegami) have a manually selectable vector (R-hue and B-hue keys) for selecting the desired skin tone. Thus, all these skin contour control circuits known so far operate without an automatic selection of the skin tone at which the circuit must be active.
A problem of such an automatic or non-automatic selection of the skin tone at which the circuit must be active is that skin tones may vary considerably from person to person. A circuit having a fixed skin contour control as described in U.S. Pat. No. 4,506,293 will therefore have to be little selective and will thus also select many unwanted background colors of the scene. A manual selection of the correct skin tone is better but is rather cumbersome, which has a detrimental influence on the convenience of use of the Ikegami circuit. An automatic control device which automatically selects the skin tone at which the circuit must be active will therefore be preferred from a user's point of view.